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Restorative & Materials · patient case question

A tooth with very little remaining coronal structure is being prepared for a gold crown. What would you add?

Patient case: Fluoride, preparation design, syphilis and patient communication

Scenario: Five short items.

  1. Retention grooves in the axial walls
  2. A greater taper to the axial walls
  3. A deeper chamfer margin
  4. Additional occlusal reduction
Show answer and explanation

Correct answer: A. Retention grooves in the axial walls

  • A. Correct. When the axial walls are short, grooves and boxes add resistance and retention form by limiting the paths along which the restoration could be displaced.
  • B. Increasing the taper reduces retention. The optimum convergence is around 6 to 10 degrees total.
  • C. The margin design determines the finish line and the bulk of material at the margin; it does not supply retention.
  • D. More occlusal reduction removes still more tooth structure and shortens the walls further — the opposite of what is needed.

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